Ventilating equipment for high speed train

ABSTRACT

A ventilating equipment for high-speed trains in which the differential flow rate between supply-air and exhaust-air is kept within certain limits to minimize an unpleasant sensation on the part of the passengers, for example, as the train passes through a tunnel at high speeds.

United States Patent I [72] Inventors Masahiko lshizawa [51] Int. Cl "F24f 7/00 Tokyo; [50] Field of Search 98710, 8, Takio Fujioka, Kudamatsu-shi, Japan 32, 33 (R), 62 [21] App]. No. 787,430 [22] Filed Dem 27 9 [5 6] References Cited [45] Patented Feb. 16, 1971 UNITED STATES PATENTS I gnee Japanese National Rail y a Hitachi. 328,818 10/1885 Simpson 1 8 98132 1,566,772 12/1925 Roth 98/33R q ymJ p 2,287,215 6/1942 Williams.... 1 98/10 2] i i y Dec-2781967 2,664,808 1/1954 Peterson 98/10 [33] Japan Primary Examiner William] Wye [31 1 42/8330. A!t0rney-Craig, Antonelli, Stewart & Hill [54] gigg EQUIPMENT FOR m SPEED AB STRACT A ventilating equipment for highvspeed trains in 7claims'7nnwing Figs which the d1fferent| al flow rate betweensppply-nlr and exhaust-air is kept within certain llmits to min mize an un- [52] us. Cl 98/8, l a t sensation on the part of the passengers, for example,

0, 2, 98/33, 8/62 as the train passes through a tunnel at high speeds.

PATENTED FEB 1 6 l9?! $563,155 sum 1 0F 2 FIG. I

FLOW QUANTITY w mmmmm ATENTFU FEB l 6 I871 SHEET 2 OF 2 L CL N W l u A. T C M DH Q A0 K w mfl M m H m w Wm M T v O A T A m EL H -m N H M .m& C S S -mwm M m |O 4 M T L E N N W m R m A 1 MN U R LL m m .0 I 62 wi FIG. 4A

00 A0 EA CA HEAD CAR m mm s23 aaag LEAVE AWAY FROM TUNNEL Y n T N A U 0 m A E w W W M A m MM Nb A w l QI n A F NW D ID,

I.2 E Q A HU A M 0 IIID. h L ||l| 6 l 1 VENTILATING EQUIPMENT FOR HIGH SPEED TRAIN This invention relates to a ventilating equipment adapted for use on a high-speed train.

With the recent trend for faster railroad transportation, trains on some lines run at speeds as high as 200 to 300 (km/hr.) and they have broughtto light various phenomena which had never been observed with trains traveling at speeds of less than 200 km./hr.

Of those phenomena that have become manifest, a most im portant one is the change of atmospheric pressure. When a high-speed train rushes into a tunnel, it causes a sudden change in the atmospheric pressure in the space between itself and the surrounding wall of the inside'of the tunnel, which in turn affects the pressure on the inside the cars of the train thereby making the passengers feel uncomfortable. In extreme cases, such pressure changes can even lead to a functional dis order of human body. The term car as used herein refers to cars of a train.

In an effort to overcome this difficulty it has hitherto been proposed to keep the cars airtight and to close the supply ports for the ventilation provided on individual cars before the train enters a tunnel so as to cut off the communication of the air inside the train from the external air that undergoes a drastic change in the atmospheric pressure; This ventilation system makes it impossible to ventilate the train as long as the train is in a tunnel and therefore the air insidea train running through a long tunnel will be increasingly polluted until it begins to prove detrimental to human health.

As an alternative, it has also been proposed to control the opening of the supply ports provided on cars in response to changes in the external atmospheric pressure. This method again has disadvantages in that the amount of ventilation is highly variable and the atmospheric pressure inside the cars is fairly susceptible to changes in the external pressure.

This invention is directed to the provision of a ventilating equipment for a train which permits little changes with time of the atmospheric pressure in the cars and enables the train to obtain a necessary rate of ventilation as the train runs into the tunnel and causes a drastic change in the atmospheric pressure in the space between the train and the surrounding wall of the inside of the tunnel. An eventual object of the invention is therefore to protect the passengers from the unpleasant sensa tion due to changes in the atmospheric pressure and ensure a healthy and comfortable traffic life. Another object of the invention is to provide a ventilating equipment capable of achieving the above object and which is'simple in construction reliable in operation with a low rate of troubles and failures, and can be manufactured at low cost.

Other objects and advantages and the construction of the present invention will be better understood from the following detailed description taken in conjunction with the accompanying drawings.

FIG. I is a side elevational view of a car equipped with a ventilating equipment of the present invention;

FIG. 2 is a diagram of a ventilation system for the car shown in FIG. 1;

FIG. 3 shows a characteristic curve of flow quantity versus static pressure of fans for use in the ventilating equipment according to the present invention;

FIGS. 4A and 4B are experimental curves representing time dependency of air pressure outside the train in the Otobasan Tunnel. Japan;

FIG. 5 is a schematic diagram of a ventilating equipment embodying the invention; and

FIG. 6 is a graph showing characteristic curves of flow quantity versus static pressure which are explanatory of the theoretical background of the present invention.

In order to attain the above-mentioned objects of the invention, a supply-air equipment and an exhaust-air equipment, both characterized by extremely small changes of flow quantity of air despite sudden changes of the atmospheric pressure on the outside, are incorporated in each car of a train in accordance with the present invention.

Referring specifically to FIGS. 1 and 2, numeral 1 indicates the body of a car. A supply-air equipment 2 consists of a duct 3 and of a supply fan 4 for supplying fresh air into the car by way of the duct 3. An exhaust-air equipment 5 consists of a duct 6 and of an exhaust fan 7 for discharging used or dusty air out of the car through the duct 6. Means such as conventional motors for driving these fans are not shown. The supply-air equipment and exhaust-air equipment that are employed in the practice of the invention are characterized by little changes of flow quantity in response to the changes of the external atmospheric pressure.

The relationship between the flow quantity and static pressure for the ventilating arrangement having the above characteristics is graphically shown in FIG. 3. The curve of static pressure relative to flow quantity is featured by a tangential gradient near In the graph, Q represents the amount of ventilation through a car in normal running condition at an external atmospheric pressure P When the car is on the normal run, fresh external air in a preset quantity O is supplied by means of the supply fan 4 into the car body 1 through the duct 3, while, at the same time, dust-laden air in an amount equal to the quantity 0,, being supplied, is discharged by the exhaust fan 7 out of the car through the duct 6.. The air pressure inside the car is thus maintained constant.

However, as the train runs at a high speed into a tunnel, the atmospheric pressure between the cars and the surrounding wall of the inside of the tunnel will drop sharply. Particularly when two trains pass each other in along tunnel, the drop of atmospheric pressure will become all the more pronounced and will change the flow quantity by the supply-air equipment accordingly. 1

As shown in FIG. 3, if the decrease of atmospheric pressure inside the tunnel due to the entry of a train as above illustrated is assumed to be A P, then this change will cause the supply-air equipment-to reduce the flow quantity by A Q and also cause the exhaust-air equipment to increase the flow quantity by A Q. Hence, the amount of ventilation through the car body I is decreased by A Q A Q. This results in changes with time of the atmospheric pressure inside the individual cars and in a disagreeable sensation among the passengers.

According to the present invention, fans are used which minimize the variation A Q (or A Q) of flow quantity in the face of a drop of the external atmospheric pressure so that the passengers are protected against any uncomfortable impact due to drastic changes of the air pressure inside the cars.

FIGS. 4A and 4B illustrate the changes of atmospheric pressure caused outside the cars of a train having an overall length of 300 m. as the train runs at a speed of 200 km./hr. through the 5008 m. -Iong OtobasanuTunnel, Japan. In FIG. 4A is shown the pressure changes outsidethe head car and in F I6. 48, those outside the rear car. This train is assumed to meet another train traveling at 180 km./hr.,. the two trains passing each other in the tunnel. As actually determined in this tunnel. the atmospheric pressure outside the train dropped by about 400 mm. Aq. when the train speed was 200 km./hr. and by as much as about 600 mm.Aq. when the train speed reached 250 km./hr, the unit mm.Aq. being a unit of pressure as shown by a water column mm.

Experiments with cars provided with ventilating ports of simple designs showed that the passengers begin to feel un pleasant as the atmospheric pressure outside the train drops suddenly by about mm.Aq. When the external pressure is decreased by more than 200 mm.Aq. the internal pressure will also drop at a rate of about 50 mmlAq. per second, thus giving a disagreeable impact upon human bodies. This disagreeable impact is governed by the amount and the rate of change of the internal pressure, especially by the latter. It is therefore important to choose a ventilating equipment which can restrict the rate of change of the atmospheric pressure inside each car to 50 mm.Aq. or less per second, even if the atmospheric pressure outside drastically changes by more than 200 mm.Aq.

For the purpose of the invention, the change A Q (or A Q) in m.3/rnin. of the flow quantity with a change A P mm.Aq. of the atmospheric pressure outside a car, that is,

is called a differential flow rate, and the performance of a ventilating equipment of the construction as shown in FIGS. 1 and 2 is represented by the differential flow rate thus defined. Experiments demonstrated that, in order to limit the rate of change of the atmospheric pressure inside the car within the range of 50 mm.Aq. or less per second while the change of the atmospheric pressure outside the car ranges from 200 to 600 mm.Aq. it is only necessary to maintain 0.0007 V m.3/min. mm.Aq. where V is the volume in cubic meters of the car to be ventilated. This indicates that the greater the V value, the higher the differential flow rate of the ventilating equipment that may be employed. Of course, it is appreciated that, within the above-specified range, the value of 7 may be increased in a tunnel where the rate of change of the atmospheric pressure outside the train is negligible, and that the value cannot be increased in a tunnel where the atmospheric pressure outside the train undergoes any substantial change. In any case, as long asn is kept within the range above defined, no drastic change will occur in the air pressure inside the car and hence no unpleasant sensation among the passengers.

Examples of fans which show very little changes in the flow quantity with respect to change of the external atmospheric pressure and which are useful in the practice of the present invention include fans of displacement type, such as Rootsblowers. Turbo-blowers having relatively high maximum static pressures ranging from 500 to 1,000 mm.Aq. are also useful for the invention because they can maintain the 11 within the range above specified.

Even turbo-blowers of relatively low maximum static pressures, say, in the range of 500 mm.Aq. Hg. or less, may be employed in the invention since the n can be confined within the above range by the adoption of a construction as shown in FIG. 5. More specifically, turbo-blowers 8 and 9 are mounted in the supply duct 3 and exhaust duct 6 of the car body 1 and conventional valves 10 and 11 providing a flow resistance are provided on the suction sides or discharge sides of the turboblowers, and thus a supply-air equipment 12 and an exhaustair equipment 13 are constructed. Here the illustration of motors for driving the turbo-blowers and other components is omitted. The operation of the ventilating equipment constructed as shown in FIG. 5 will now be described.

In FIG. 6 the curve (a) represents the relation of flow quantity (along the axis of abscissa) versus static pressure (along the axis of ordinate) of a turbo-blower. In a state where the flow resistance is extremely small or almost zero, the actuating point of the blower is at point A. If the pressure on the suction side drops from the pressure on the discharge side by AP or if the pressure on the discharge side rises above the pressure on the suction side by AP, the actuating point will move to B and the flow quantity will decrease by A0,. Conversely if the pressure on the suction side rises above the pressure on the discharge side by AP or if the pressure on the discharge side drops from the pressure on the suction side by AP, the actuating point will be shifted to C and the flow quantity will increase by AQ Thus, under the conditions above described, the flow quantities of the supply fan and exhaust fan will be materially varied with the changes of the external atmospheric pressure.

These characteristics of turbo-blowers are modified in the fans that are used in the present invention by the provision of flow-resistance valves of any conventional construction on either the suction sides or the discharge sides of the blowers.

The curve (b) in Fig. 6 indicates the flow quantity versus resistance characteristic of a duct incorporating such a throttle valve. Here the actuating point of the turbo-blower including the duct and flow-resistance valve is at D. If the external atmospheric pressure changes by AP as noted above, the curve (12) will move parallelly upward or downward by a distance AP to form a new curve (b) or (b). Accordingly, the actuating point of the turbo-blower will be shifted to either E or F, and the flow quantity will be decreased by AQ' or increased by AQ' As a result, the actuating point of the ventilating equipment including the flow-resistance valve, duct and turbo-blower will be moved to D, E and F correspondingly to the points D, E and F, and the working characteristic will be represented by the curve E'-D-F. Since the tangential gradient of such a working characteristic ED'F is more acute than that of the working characteristic E-D-F-, the changes AQ, and AQ' of the flow quantity with the change AP of the external atmospheric pressure may be kept small, and the flow-resistance valves are suitably adjusted so as to maintain such changes within the range of 1 above specified.

Although the provision of flow-resistance valves on the turbo-blowers will reduce the total flow quantity to Q',,, this can be compensated for by the use of fans having a combined capacity increased by the quantity equivalentto the above decrement of the flow quantity.

As stated hereinbefore, the present invention permits only little changes in the rate of ventilation in response to a sudden and sharp increase or decrease of the atmospheric pressure around the train entering a tunnel and therefore causes only negligible changes in the atmospheric pressure inside the cars and gives no unpleasant impact upon the passengers. Also, because fans capable of assuring a necessary rate of ventilation can be used, fresh air can be supplied to the cars at an advantage. A further advantage of the invention is that, with a ventilating equipment using flow-resistance valves, regulation of the flow quantity for the ventilation is made possible only if the openings of the valves are adjustable.

We claim:

1. A ventilating equipment for a high-speed train car which comprises:

a supply-air equipment for supplying fresh air into the car from the outside thereof; and.

an exhaust-air equipment for exhausting dusty air from said car to the outside thereof, said supply-air equipment and exhaust-air equipment each having a differential flow rate which is a value of not more than 0.0007 X V(cubic meters/minute mm.Aq. respectively, where V is the volume of the interior portion of the car in cubic meters. 2. A ventilating equipment according to claim 1, wherein said supply-air equipment and exhaust-air equipment each include a blower of the displacement type.

3. A ventilating equipment according to claim 1, wherein said supply-air equipment and exhaust-air equipment each includes a turbo-blower and flow-resistance valve means provided on either the suction side or the discharge side of each respective turbo-blower.

4. A method of limiting the rate of change of atmospheric pressure within the interior portion of a car of a rapidly moving train comprising the steps of:

transferring air across the boundary between said interior portion of said car and the atmosphere external to said car at a predetermined flow rate so as to ventilate said car; and

maintaining any change in the flow rate of said air being transferred to be no greater than 0.0007 V cubic me-- ters/minute with respect tochanges in the atmospheric pressure in millimeters of Aq. external to said car, where V is the volume in cubic meters of the interior portion of the car to be ventilated.

5. A method according to claim 4, wherein the step of transferring includes a the step of supplying fresh air into said car from the atmosphere external to said car.

ferring further includes the step of exhausting air from the interior portion of said car to the atmosphere external to said car. 

1. A ventilating equipment for a high-speed train car which comprises: a supply-air equipment for supplying fresh air into the car from the outside thereof; and an exHaust-air equipment for exhausting dusty air from said car to the outside thereof, said supply-air equipment and exhaustair equipment each having a differential flow rate which is a value of not more than 0.0007 X V(cubic meters/minute mm.Aq. respectively, where V is the volume of the interior portion of the car in cubic meters.
 2. A ventilating equipment according to claim 1, wherein said supply-air equipment and exhaust-air equipment each include a blower of the displacement type.
 3. A ventilating equipment according to claim 1, wherein said supply-air equipment and exhaust-air equipment each includes a turbo-blower and flow-resistance valve means provided on either the suction side or the discharge side of each respective turbo-blower.
 4. A method of limiting the rate of change of atmospheric pressure within the interior portion of a car of a rapidly moving train comprising the steps of: transferring air across the boundary between said interior portion of said car and the atmosphere external to said car at a predetermined flow rate so as to ventilate said car; and maintaining any change in the flow rate of said air being transferred to be no greater than 0.0007 V cubic meters/minute with respect to changes in the atmospheric pressure in millimeters of Aq. external to said car, where V is the volume in cubic meters of the interior portion of the car to be ventilated.
 5. A method according to claim 4, wherein the step of transferring includes a the step of supplying fresh air into said car from the atmosphere external to said car.
 6. A method according to claim 4, wherein the step of transferring includes the step of exhausting air from the interior portion of said car to the atmosphere external to said car.
 7. A method according to claim 5, wherein the step of transferring further includes the step of exhausting air from the interior portion of said car to the atmosphere external to said car. 